Polysulfone Gate Dielectrics for Low-Leakage MOSFETs

The patent employs composite polymeric dielectric materials that combine multiple functional components: (1) polymeric backbone structures providing mechanical flexibility and processability, (2) inorganic filler particles or nanocomposite structures providing low dielectric loss and reduced leakage current, and (3) surface-modifying layers enabling compatibility with both solution-phase and vapor-phase deposition techniques. This composite approach allows the dielectric material to simultaneously achieve low leakage current density while maintaining ease of manufacture through versatile deposition method compatibility.

The patent utilizes parameter changes in the polymeric dielectric materials, specifically adjusting the glass transition temperature (Tg) to optimize performance. By selecting polymers with Tg above the processing temperature but below the deposition temperature, the material maintains mechanical stability during fabrication while achieving low leakage current. The patent also adjusts dielectric constant, film thickness, and crosslinking density to simultaneously reduce leakage current and maintain compatibility with solution-phase and vapor-phase deposition processes.

The patent applies beforehand cushioning by incorporating thermally stable polymeric structures and crosslinking mechanisms that prevent degradation and leakage current increase during thermal annealing. The polymeric dielectric materials are designed with high Tg values and robust molecular structures that resist thermal-induced leakage. Crosslinking agents or thermally stable adducts are pre-introduced to create a network structure that maintains electrical stability even after exposure to high-temperature annealing processes, thus cushioning against the harmful thermal effects before they can degrade the material.

The patent changes the thermal stability parameters of the polymeric dielectric materials by selecting polymers with glass transition temperatures significantly above the annealing temperature. This parameter change ensures that the material remains in a glassy, stable state during thermal processing, preventing the mobility increase that would lead to higher leakage current. The patent also adjusts the crosslinking density and molecular weight to optimize thermal resistance, allowing the material to withstand thermal annealing without significant leakage current increase.

The patent applies preliminary action by performing crosslinking or surface modification of the polymeric dielectric material immediately after solution deposition but before subsequent processing steps. This preliminary crosslinking creates a stable, insoluble network that prevents material dissolution or degradation during later vapor-phase deposition or thermal processing. The surface is pre-prepared with adhesion promoters or protective layers that ensure material integrity is maintained throughout the fabrication sequence, allowing solution-processability to be achieved without sacrificing reliability.

The patent employs composite polymeric dielectric materials that combine soluble polymeric components with insoluble crosslinking agents or nanocomposite fillers. The soluble portion enables easy solution processing and deposition, while the insoluble crosslinked network or nanocomposite structure provides mechanical and chemical stability during subsequent processing steps. This composite structure allows the material to be solution-processed at low cost while maintaining integrity through the robust crosslinked framework that resists degradation during vapor-phase deposition and thermal annealing.

The patent introduces an intermediary surface treatment layer or plasma treatment process between the polymeric dielectric deposition and the subsequent semiconductor layer formation. This intermediary treatment smooths the polymeric surface at the molecular level, filling in micro-roughness and creating a uniform interface. The intermediary plasma treatment or surface coating acts as a mediator that transforms the inherently rough polymeric surface into a smooth interface compatible with stable TFT operation, without requiring complete redesign of the polymeric material itself.

The patent changes the surface energy and roughness parameters of the polymeric dielectric material through controlled deposition conditions, solvent selection, and post-deposition annealing. By adjusting these parameters, the patent achieves smoother surfaces that are compatible with stable TFT performance. The polymeric material is deposited under optimized conditions that minimize surface roughness, and subsequent gentle annealing processes further smooth the surface without causing degradation, thereby achieving manufacturing precision while maintaining fabrication productivity.